Successfully complete any mission and earn as little money as possible. Save the game, then replay that mission again. Earn as much money as possible and create a save point immediately before escaping from the level. Then, escape from the level and the mission review screens will appear displaying your new account balance. Any additional money earned from playing the mission the second time will be added to your account balance. Next, go back to the first screen, then select to replay the mission. A message warning that your progress will be lost will appear. Ignore this message, as your save points and account balance will not be reset. When the mission begins again, load the save point created immediately before escaping from the level. Escape from the level and the additional money will be added to your account balance again. Repeat this process as much as desired to get an unlimited amount of money.

Infinite saves in Normal and Expert mode

While saving during a mission on the Normal or Expert difficulty setting, press Start before the "Save Complete" message appears and it will not count towards your limit of saves. Note: This will not harm your saved game.

Free intel

Purchase all the intel when a mission starts. Make a note of it, then pause the game and choose to restart the mission. You will have your original starting money, and the intel will now be available for purchase again even though you know what it contained.

Alternate background

Successfully complete the game to alternate the main menu background.

Newspaper headlines

After completing a mission, the newspaper headline will vary depending on how you did. If you did poorly, the paper will say so in the paragraph. If you shoot very little and use mostly hand to hand it will say that there is not enough information to make a ranked description of you. If you completed the mission with high accuracy, it will state that you are a well trained marksman. Try completing missions differently to see different headlines.

License plates

Look at the license plates of cars in different levels. In the "A New Life" mission, the license plate of all the cars reads BADBLOD (Bad Blood). In the "A House Of Cards" mission, the license plate of the first limo at the casino reads "L1MONEY", or something similar.

Alternate ending sequence

In the final level "Requiem", Diana will give you the antidote to the death serum. You will fade in and out of life (power bar rises and drops to the beat of Agent 47's heart) while the credits roll. If you do nothing, the game will end. However, if you press the Left Analog-stick Up and Down (or any other buttons) repeatedly, you will come back to life and your mission will be to leave no witnesses. -From: PRIMEBEEF2006

Easy "Silent Assassin" rank in A New Life mission

Start the mission with no weapons except for your standard equipment. First, go to the back of the food truck when the delivery man is walking off. Pick up the donuts, then take them around the corner so that nobody can see you. Put them on the floor and then scroll through your inventory. Select the "Sedative Syringe", then look down at the donut box and inject the sedative into them. Pick up the donuts again, put the syringe away, then go back to the food truck. Drop the box of donuts on the floor directly behind it, then walk away. The delivery man will pick up the donuts and take them to the FBI van across the road. Wait a short time and an short intermission sequence inside the truck will appear, showing the FBI agents falling asleep. Go to the back of the truck, open the door when prompted, and go inside. When inside the FBI truck, suit up as an FBI agent, and steal the video tape, which should be on the left side of the van as you go in. Do not pick up any weapons. Leave the vehicle and go up to the front of the house and walk inside. Go out the back towards the shed, which is in the top right hand corner. Wait until there is nobody around. If the pool man goes in, do not try to follow him or your suspicion bar will go into the yellow. When there is nobody around, pick the lock, go inside, and pick up the lighter fluid. Exit the shed, go right, and then go towards the pool. Over to your right is a barbecue. Go up to it and you will get the "Rig the Barbeque" option. Select it, then go inside the house and wait under the stairs. Stand around for a short time and a short intermission sequence will show a woman being burned alive. When she is dead, go back outside and pick up the microfilm that she is wearing around her neck. Go back inside, then go up the stairs. Turn right across the landing, then go straight. Open the first door on your right, then go in and wait behind the L-shaped wall. If the main target is already there, wait for him to leave, then wait awhile for him to return. When he returns, make sure he has his back towards you, then fibrewire him. When he dies, drag his body to the place you were hiding (the L-shaped wall). Then, sprint out of the house towards your escape as quickly as possible. If done in a short time, you should get either a "Hitman" rating or "Silent Assassin" rank. Either way, you will get $100,000 and if you have already completed the game you can purchase an additional upgrade to your custom weapons whenever you select a mission.

Easy "Special Rating" achievement in A New Life mission

You will need a minimum of ten headshots for this achievement as well as a silenced sniper rifle, and the foil case. In the A New Life mission, select your sniper rifle as your only weapon. Walk around to the tree house at the end of the street where you find the air rifle. It is at the exclamation point near the ladder in the middle of the map. Unpack your rifle and snipe every FBI agent that gets within your sights. Shortly afterwards, two cars will arrive carrying more agents. Snipe these as well, making sure not to hit any civilians or the dog. You should end up with two guards remaining in the surveillance van out front, one at the front door, and one at the back door. Pack your sniper into the foil case and walk back to the surveillance van, but turn into the open garage on the left. Unpack and assemble the rifle in the back corner, dropping the rifle on the floor of the garage. Walk to the other side of the street and poison the donuts when no one is looking. Wait for the caterer to deliver the donuts and watch the intermission sequence. Enter the van when the jogger is out of sight. Change into an FBI suit and use the phone to call the witness. Leave the van immediately and pick up your rifle. Snipe the guard at the front door and look to the left. You should see the witness on the phone in the living room window; snipe him as well. Enter the house through the door to the left of the garage. Walk north to the bedroom with the open window and climb out. Walk to the back corner of the yard and snipe the final FBI agent at the back door. Pack your sniper rifle up and enter the window again. Leave the case in the bedroom and get your sedative syringe ready. Find the wife of the witness running anxiously through the house and sedate her to take the microfilm necklace. Pickup your sniper case on the way out. Change back into your suit you left in the surveillance van, then proceed to the exit to gain the achievement and read an interesting headline.

Secret "Slugger" rank in A New Life mission

Kill everyone in the mission, even the dog, with the baseball bat to get the "Slugger" special rank.

Quickly get FBI clothes in A New Life mission

Normally to get the FBI clothes, you would drug the donuts and feed them to the feds in the van. You would then see them get sick and pass out before entering the van again. You do not actually have to do this. As soon as you see them getting sick, you can enter the van. They will be so sick, they will not notice.

Body bag in A New Life mission

At the beginning of the mission, stick your mine in the catering case. The man will carry it out back later. When he is in the back, blow the case. The agents will crowd around and one will say "Damn, not another one. I hate having to do this." or something similar. He will then put the man in a body bag and drag him into another room.

Easy "Silent Assassin" rank in A Vintage Year mission

You do not need any weapons for this mission; you only need the Anti Personnel Mine, Sedative Serum, and Coins. At the start of the mission, do not follow the tourists. Instead, go west along the outer wall. When you get to the corner you will see a broken truck. Check your map for guards. There should be one south of your location. Go around him using trees and bushes as your cover. You do not need to crawl, as he usually does not notice if you are a fair distance away. Once you pass him use the serum and sedate him from the back. Take his clothes and leave him there. Get in the rear compartment of the broken truck then get on its roof. From there, get on the storage room roof. Slowly crawl through there to the hole in the roof then jump in. The other guards will not pay much attention to you since you are wearing the guard's clothes. You do not need to worry about the alert level, even if it rises. Run out of the storage facility and across the square. Go to the right from the mansion and through the wooden door. Keep running straight and take the first door to the left that leads to the basement. You should see a guard as soon as you open the door. Place a mine next to him on the gadget with rope. Check the map until you notice a red blip (the target) enter a small square opening below you. As soon as this happens, get a few yards back from the explosive. Throw a coin on the ground so the guard comes to it. Detonate the mine once guard clears off. By doing this, the guard will not die and you will not suffer a penalty for an unnecessary kill. Wait for some guards to run to the place you are at, then make your way back to the mansion. Instead of the front entrance, use the small door on the left of it. This will lead you just a bit underground. Go to the door on the right and wait (with your map on) for the guard who is parallel to you to come by and turn around (starts marching back). Open the door, go to him and sedate him. Drag the guard to the nearest room to your right and take his clothes. He is a different type of guard who can move around the house freely. Dressed as a VIP guard, go to second floor and into the room with your target. Do not bother to crawl. Go to the balcony and throw a few coins on the ground to get his attention. Once he comes to check it out, get behind him and push him over the rail. Both targets are now dead. Check your map. There should be a "!" mark nearby, which is a window. Get out of it and down the roof. Get off the roof and go right behind the corner. There will be a narrow passageway down to the plane. Notice this is the place where the second target has landed. Do not forget to pick up his weapon on your way down. When you are near the plane, crawl by the one worker and two guards that are nearby. Ignore the worker and walk around the path. Get into the plane and complete the mission.

Play piano in A Vintage Year mission

To play the piano, walk up to it and shoot it in different locations to make different sounds.

Easy "Silent Assassin" rank in Amendment XXV mission

Start the mission with absolutely no weapons. Go into the east wing, pass the metal detectors, and move straight ahead. Pass the red ropes and go left to the bathroom. Prepare to use your sedative syringe. Go to the corner next to the door. Wait for the museum attendant to enter and use the bathroom. Sneak behind him and sedate him. Take his clothes and drag him to a corner. Get as close to it as you can. Failing to do so might result in getting the guards attention. Get out of the bathroom and go directly to the museum attendant entrance. Keep going, and at the end of the hall, go to the door on the left to get to the outside. Look for the Marine and get behind him. Take his clothes and do not worry about the M14. You will not need it and it only gets in the way. Go back inside and find the hallway to the main building. Towards the end of the hallway is a door that will take you to the roof. Go up, and find the scaffold into the main building. Go up, but stop before you reach the top, There will be two workers looking at the window. If they see you climbing, they will raise the alarm. Wait for them to turn around, then climb to the top. Go in the window. The room straight ahead has a camera. Avoid going in it. Instead, go left to the room being remodeled and keep going through doors until you find the next window. Make sure that the patrolling Marine is not in the room any more. Then, climb out the window and go down the next scaffold. When you are down there, turn left and get close to the edge to climb down the wall. There is a lattice that will take you to the garden. If you did this in a timely fashion you will be at the garden before the Vice President is there with his dog. There might be a Secret Service guard patrolling. Avoid raising suspicion. Walk, or if alone, run to the West Wing towards the only clear window in the Oval Office. Parchezzi is in the Oval Office and will get close to the window when the Vice President approaches it. Pull a wall mine from your inventory. Parchezzi might see you doing this, but he will not do anything about it. Set it up as close to the window as possible, then run back to the roof you came from. Climb up and be ready with the detonator. Make sure you are close enough to detonate. As soon as the Vice President is at the window, wait about two seconds and Parchezzi will come to talk to him. Detonate, then get rid of the detonator and climb back up the scaffold to the main building. Go back the same way you came from, avoiding the cameras. Go down the other scaffold, and go into the hallway. Walk out, but do not forget to put your suit back on. Your bar might show a little green or maybe even yellow, but it is acceptable. Just walk out through the metal detectors and escape.

Keep custom weapons in Amendment XXV mission

There are two methods to take weapons such as the Silverballers, etc. through the White House and bypass the metal detectors. The first method is to go to the other end of the parking lot when you start. Look to the left when you get to the end and you should see a ICA storage box. Put your custom weapons in it, then go into the White House through the double doors at the front and walk through the metal detectors. Remember that fibre wire, syringes, mines, and the detonator will not activate metal detectors. Go to the other end of the lobby. There should be a guard behind a rope watching some double doors. Go into the door on his left (the toilet), and stand facing the corner furthest away from the door and the toilet. Wait for the museum member or staff to walk in and for the door to shut behind him. Take out a silent weapon (fibre wire or syringe) and use it on him before he opens the door. Take his clothes and hide him as best as possible against the corner furthest from the toilet, but closest to the door. Check the map. If there is an innocent person in the lobby looking in your direction, wait for him to start walking away before opening the door or he will see the body and you will be shot. Open the door when you get the chance. While staying behind the ropes, walk across the width of the lobby and through the door on the other side. Go directly to the other end of the next corridor and take the last door on the left. This should lead you outside. When you get the chance to take out the U.S. Marine who patrols here, do so then hide him behind the big steel block. Take his clothes and gun. Walk back out the front doors and you should beep when going through the scanner, but the guards will not shoot you. Take your weapons out of the storage box from the side of the building and conceal them. When you go back in you should beep, but once again the guards should ignore it as long as you have your M14 at the ready.

For the second method, do the same as above, but when the Marine is out of the way, do not take his clothes or his gun. Work your way back out the front doors and go to the storage box. Take out a weapon and hold the weapon so you can throw it. Aim up and past the fence, towards the White House wall. Bounce your weapon off the wall and it will land on the other side of the fence. Do this with all your weapons, then go back to the area where you incapacitated the Marine. Walk down the alley and pick up your guns, then conceal them. Make sure you are far enough behind the wall for the guards out the front not to see you or they will shoot at you. Note: This method is useful if the game glitches and the Marines shoot at you even when you look like one.

Easy "Silent Assassin" rank in Curtains Down mission

This trick requires that you have the scope for your Silverballer. When the mission begins, run up the steps and to the right. Toss a bomb and quickly pick the lock on the first door on the left. Walk in and explode the bomb. Wait a moment, then snipe the man up in his private box and the actor walking on stage. Put your gun away and get out of there. If done correctly, you will get a "Silent Assassin" rank in under a minute.

Rat Club in Curtains Down mission

In the basement during the mission, there are three rats. Kill them and a keycard labelled "Rat Club" will appear on the nearby table. Go up to where you can find the keycard for the light control room and there will be a door with a keycard slot. Use the "Rat Club" keycard on the door. Inside are rats boxing (with gloves on) and playing poker.

As soon as the mission starts, you will see a guard shack. Run to the side door and enter. The cop inside will tell you to leave. Leave, then wait a moment and walk back in. He will be walking the other way and will not see you. Quickly sedate or kill him. Take his gun and clothes. Also, check the gun box next to the door for extra ammunition.

Dancing Agent 47 in The Murder Of Crows mission

Get one of the disguises for the Salsa, Rock, or Blues bar. Then, move Agent 47 on the dance floor and allow the game to idle. After a few minutes, he will begin to dance. Note: If you move him around while he is dancing, he will stop; however, you can still move the camera around while he dancing.

Easy "Silent Assassin" rank in 'Till Death Do Us Part mission

No guns are needed in this mission; all you need are two poison syringes. Start the mission by heading towards the party. Wait for the drunk guest to vomit and go to the shed on the left. Follow him into it. Wait for him to sit and fall asleep, then take his party invitation. You do not need to take his clothes. Go to the main house and enter. Stay to the right of the stairs. If the bride is there do not talk to her, as this will take your time. Instead, keep going to the end of the foyer. To your right is the kitchen. Check your map to make sure no one is in it, or is going to it, or is behind you. When it is clear, go in the kitchen. You will find the wedding cake. Take out a poison syringe and inject the cake. Go into the room directly behind you. Stay next to the wall so when the priest enters he will not see you. Wait for the groom to come into the kitchen and take a bite from the cake. He will fall dead at the kitchen door. When you are clear, go back in the kitchen and drag his body. Hide him in the container at the corner of the kitchen. Get out of the kitchen using the same way you came in. Go straight for the bathroom. Make sure no one is in there and pick the lock on the door next to the toilet room. Do not go into the reception area. Instead, keep going straight to the bathroom. To the left is a door that is locked. Make sure no one is in the bathroom and pick the lock. There is a guard patrolling the next hallway. Make sure he is walking away from the door as you open it, then run straight for the door in front of you just to hide for a little while. Alternately, if you think you are fast enough and can make it for the stairs before the guard turns around, do that instead. Go up the stairs and to the left, staying as close to the wall as possible. There are guards just around the corner as you enter Pappy's room through the door left of the stairs. Go in the room and find the area where the TV is located. Get your syringe out and ready and enter the closet. Wait and Pappy will eventually come up to the room to watch television. Come out and inject him with the poison syringe. Then, go back down the same way you came up. Make sure the guard does not see you coming down the stairs, as no one is allowed to the second floor. Use the same way to get out -- through the bathroom, then directly to the outside. Walk, and do not run. Also, if you suited the drunk guest put your suit back on to avoid the overages of suit retrieval. If your bar is a little yellow, it is acceptable; you will still get the "Silent Assassin" rank.

The Simpsons reference

In The Murder Of Crows mission, kill at least one police officer. At the end of the mission, the newspaper article will read "Police intend to put a low priority on investigating the deaths of the security officials. NOPD chief Wiggum states, 'The deaths of our fellow officers were tragic. We will find out who killed them.'", or something similar. -From: shadowofthereal1